The present invention relates to an apparatus and a method for extending the useful range of direct angle of attack measurements with non-movable sensors.
Present pressure type non-movable angle of attack sensors use a ratio of two measured or sensored pressure differentials to determine angle of attack. A hemispherical end sensor is described in U.S. Pat. No. 3,318,146. Angle of attack and angle of side slip both are calculated from the pressure signals present at five ports on the end.
Sharp tipped pitot static tubes with angle of attack sensing ports, are shown in U.S. Pat. Nos. 4,096,744 and 4,378,696. These patents show probes providing differential pressures which are used for determining angle of attack. In patent '696, a combination of differential pressure at two ports, measured pitot pressure and measured static pressure is used. In patent '744, measured pitot pressure, pressure at one of the angle of attack sensitive ports and measured impact pressure are utilized for the calculations. However, in both these probes the angle of attack measurement is based upon pressure differentials which, while having the ability to measure angle of attack reliably at most normal angles of attack, have limitations when extremely high angles are measured.